Overclocking the CPU historically was found with computer chess enthusiasts who were strong drivers of CPU performance.
Modern gaming motherboards now ship with a sophisticated BIOS or UEFI that provides enthusiasts with complete control over the CPU and RAM settings.
AMD Overdrive and the Intel Desktop Control Center can be used in Windows to adjust CPU parameters.
Overclocking a CPU has proportional increase in power consumption. Our Phenom II 965 BE C3 is rated at a maximum of 125 W while the older C2 is rated at 140 W maximum. The Phenom II 965 is natively 3.4 GHz and its supplied with 1.4 V max to provide stable operation.
Raising the clock speed to 4 Hz is about 17% faster so our C3 processor will need 145 W of power maximum.
Intel and AMD use locked multipliers on cheaper processer lines as these are not intended for gaming use. The lock came from the early Pentium period when some unethical vendors would swap a CPU for a cheaper model and overclock it to a more expensive SKU.
The old processors from Intel before they finally moved to an integrated memory controller used a front side bus which today is used mostly for memory timing.
AMD markets the black edition and Intel markets the extreme edition processors to overclocking enthusiasts. These do not have a locked multiplier. Our Phenom II X4 965 is the black edition which is targeted to the gaming community.
The old FSB is now best seen as the main memory clock. Dynamic RAM has lagged CPU performance for decades. Advances in semiconductor lines are the reason for DDR2 and DDR3. DDR4 simply is a continuation of the lower power as the sizes get smaller.
The base clock of 200 MHz has been used now for several years. This is one area that enthusiasts often alter in a bid to increase the overall system performance.
With the M5A99FX motherboard and DDR3-2133 the CPU can operate at DDR3-1600 which the top JEDEC speed. Overclocked it easily achieves DDR3-1866 which improves the main memory performance considerably.
Sometimes RAM is not recognized properly due to limitation problems in the SPD tables. Typically such settings need to be done in the BIOS where it easier to recover from an error in the configuration the causes the machine to freeze.
DDR3 was extended by Intel with the XMS profiles due to the slow introduction of DDR4. DDR4 adopted the XMS speeds and added more to the tables.
Some extreme enthusiasts resort to increasing the maximum CPU voltage. This will lead to a significant increase in the CPU dissipated power and generally requires water cooling.
Our Phenom II 965 BE C3 uses 1.4 V natively and increasing it to 1.5 V will significantly affect the cooling capacity required.
Our Phenom II X4 965 has a default multiplier of 17. With the older M2N-VM CSM board, we found that using a higher multiplier was not successful. This is likely due to the DDR2 timings.
With the newer M5A99FX PRO R2.0, increasing the FSB clock from 200 to 235 MHz raised the system performance up to desired 4 GHz operation which is considered standard for the processor. We are testing the overclock with games and applications for a long period of time to be sure the system is stable. Many games are CPU intensive and we have found Age of Empires to be much more fluid in game play.
Thermal interface material is not created equal. Using a better thermal grease can be material with overclocking. Our Phenom II 965 was able to increase the overclock from 3.8GHz to 4Ghz and the CPU is thermally stable.
Its probably obvious that to overclock our Phenom beyond 4 GHz is going to require water cooling or beyond.
Many vendors compete for water cooling however there are many options for the DIY enthusiast. The Cooler Master Hyper 212 Evo is one of the most popular after market coolers available.